1. Field of the Invention
The present invention relates to a focusing function of an image recognition camera for use for positioning a chip and a substrate with high precision in a bonding apparatus. The present invention relates to an improvement of a focusing means of a chip recognition camera particularly in image recognition devices for automatically performing image processing without fuzziness.
The present application is based on Japanese Patent Application No. Hei. 10-321279 which is incorporated herein by reference.
2. Description of the Related Art
In the related art, in order to focus an image recognition device in a bonding apparatus, there were a method in which automatic focusing was performed by means of an optical unit with a built-in laser displacement meter, and a method in which focusing was performed on the basis of the thickness of a substrate and the thickness of a chip which were set in advance.
However, in the method in which automatic focusing was performed by an optical unit with a built-in laser displacement meter, there was a defect that the bonding apparatus became expensive because two optical units were required on the chip side and on the substrate side. On the other hand, in the method in which focusing is performed on the basis of the thickness of a substrate and the thickness of a chip which are set in advance, at the present time where positioning with high precision is required as chips are reduced in size, there arises a problem that the position of the chip recognition camera must be set again manually if the amount of scattering in the length of the bonding tool and the thickness of the chip exceeds the focal depth of a lens.
It is an object of the present invention to provide a device by which automatic focusing of an image recognition camera for a chip can be achieved at a comparatively low cost in a bonding apparatus, and, hence, to provide a bonding apparatus in which image processing can be performed on the basis of a sharp image without fuzziness, so that a chip can be positioned on a substrate with high precision.
In order to solve the foregoing object, according to the present invention, there is provided a bonding apparatus. The bonding apparatus comprises a bonding tool for holding a chip mounted on a mount surface, an elevating mechanism for elevating the bonding tool, a chip recognition camera for taking a picture of the held chip from a lower side of the chip, a detecting device for detecting a contact between the chip on the mount surface and the bonding tool, and a controlling device for displacing the bonding tool in a direction of height from a position where the detecting device has detected the contact between the chip and the bonding tool by a quantity equal to a difference in the height direction between the mount surface and a focal position of the chip recognition camera to thereby place the bonding tool above the chip recognition camera.
Features and advantages of the invention will be evident from the following detailed description of the preferred embodiments described in conjunction with attached drawings.